Method and apparatus for performing fast power control in a mobile communication system

ABSTRACT

A method and apparatus for controlling transmission power in a mobile communication system is disclosed. The method disclosed provides for a closed-loop power control method for variable rate transmissions. The power of transmissions is varied in accordance with the rate of the frames of data being transmitted. The transmission power between the rates can be a fixed or variable difference.

This is a Continuation Application of U.S. Serial application Ser. No.08/559,386, filed Nov. 15, 1995, now issued as U.S. Pat. No. 6,137,840,which is a Continuation-In-Part Application of U.S. application Ser. No.08/414,633, filed Mar. 31, 1995 now abandoned, and the File-WrapperContinuation of Ser. No. 08/958,822, filed Oct. 27, 1997 now issued asU.S. Pat. No. 6,035,209, and entitled “Method and Apparatus forPerforming Fast Forward Power Control in a Mobile Communication System.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to communication systems. Moreparticularly, the present invention relates to a novel and improvedmethod and apparatus for controlling transmission power in a mobilecommunication system.

II. Description of the Related Art

The use of code division multiple access (CDMA) modulation techniques isone of several techniques for facilitating communications in which alarge number of system users are present. Other multiple accesscommunication system techniques, such as time division multiple access(TDMA) and frequency division multiple access (FDMA) are known in theart. However, the spread spectrum modulation technique of CDMA hassignificant advantages over these modulation techniques for multipleaccess communication systems. The use of CDMA techniques in a multipleaccess communication system is disclosed in U.S. Pat. No. 4,901,307,entitled “SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USINGSATELLITE OR TERRESTRIAL REPEATERS”, assigned to the assignee of thepresent invention, of which the disclosure thereof is incorporated byreference herein. The use of CDMA techniques in a multiple accesscommunication system is further disclosed in U.S. Pat. No. 5,103,459,entitled “SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMACELLULAR TELEPHONE SYSTEM”, assigned to the assignee of the presentinvention, of which the disclosure thereof is incorporated by referenceherein.

CDMA by its inherent nature of being a wideband signal offers a form offrequency diversity by spreading the signal energy over a widebandwidth. Therefore, frequency selective fading affects only a smallpart of the CDMA signal bandwidth. Space or path diversity is obtainedby providing multiple signal paths through simultaneous links from amobile user through two or more cell-sites. Furthermore, path diversitymay be obtained by exploiting the multipath environment through spreadspectrum processing by allowing a signal arriving with differentpropagation delays to be received and processed separately. Examples ofpath diversity are illustrated in U.S. Pat. No. 5,101,501 entitled“METHOD AND SYSTEM FOR PROVIDING A SOFT HANDOFF IN COMMUNICATIONS IN ACDMA CELLULAR TELEPHONE SYSTEM”, and U.S. Pat. No. 5,109,390 entitled“DIVERSITY RECEIVER IN A CDMA CELLULAR TELEPHONE SYSTEM”, both assignedto the assignee of the present invention and incorporated by referenceherein.

A method for transmission of speech in digital communication systemsthat offers particular advantages in increasing capacity whilemaintaining high quality of perceived speech is by the use of variablerate speech encoding. The method and apparatus of a particularly usefulvariable rate speech encoder is described in detail in U.S. Pat. No.5,414,796, entitled “VARIABLE RATE VOCODER”, assigned to the assignee ofthe present invention and incorporated by reference herein.

The use of a variable rate speech encoder provides for data frames ofmaximum speech data capacity when said speech encoding is providingspeech data at a maximum rate. When a variable rate speech coder isproviding speech data at a less than maximum rate, there is excesscapacity in the transmission frames. A method for transmittingadditional data in transmission frames of a fixed predetermined size,wherein the source of the data for the data frames is providing the dataat a variable rate is described in detail in copending U.S. Pat. No.5,504,773, entitled “METHOD AND APPARATUS FOR THE FORMATTING OF DATA FORTRANSMISSION”, assigned to the assignee of the present invention, ofwhich the disclosure thereof is incorporated by reference herein. In theabove-mentioned patent application a method and apparatus is disclosedfor combining data of differing types from different sources in a dataframe for transmission.

In frames containing less data than a predetermined capacity, powerconsumption may be lessened by transmission gating a transmissionamplifier such that only parts of the frame containing data aretransmitted. Furthermore, message collisions in a communication systemmay be reduced if the data is placed into frames in accordance with apredetermined pseudorandom process. A method and apparatus for gatingthe transmission and for positioning the data in the frames is disclosedin U.S. Pat. No. 5,659,569, entitled “DATA BURST RANDOMIZER”, assignedto the assignee of the present invention, of which the disclosurethereof is incorporated by reference herein.

A useful method of power control of a mobile in a communication systemis to monitor the power of the received signal from the mobile stationat a base station. The base station in response to the monitored powerlevel transmits power control bits to the mobile station at regularintervals. A method and apparatus for controlling transmission power inthis fashion is disclosed in U.S. Pat. No. 5,056,109, entitled “METHODAND APPARATUS FOR CONTROLLING TRANSMISSION POWER IN A CDMA CELLULARMOBILE TELEPHONE SYSTEM”, assigned to the assignee of the presentinvention, of which the disclosure thereof is incorporated by referenceherein.

In a communication system that provides data using a QPSK modulationformat, very useful information can be obtained by taking the crossproduct of the I and Q components of the QPSK signal. By knowing therelative phases of the two components, one can determine roughly thevelocity of the mobile station in relation to the base station. Adescription of a circuit for determining the cross product of the I andQ components in a QPSK modulation communication system is disclosed inU.S. Pat. No. 5,506,865, entitled “PILOT CARRIER DOT PRODUCT CIRCUIT”,assigned to the assignee of the present invention, the disclosure ofwhich is incorporated by reference herein.

In an alternative continuous transmission strategy, if the data rate isless than the predetermined maximum, then the data is repeated withinthe frame such that the data occupies the full capacity of the dataframe. If such a strategy is employed, power consumption andinterference to other users may be reduced during periods of datatransmission at less than the predetermined maximum by reducing thepower at which the frame is transmitted. This reduced transmission poweris compensated by the redundancy in the data stream and can offerbenefits in range for a fixed maximum transmission power.

A problem that is encountered in controlling transmission power in thecontinuous transmission strategy is that the receiver does not know thetransmission rate a priori and as a result does not know the power levelthat should be received. The present invention provides a method andapparatus for controlling transmission power in a continuoustransmission communication system.

SUMMARY OF THE INVENTION

The present invention is a novel and improved method and apparatus forclosed loop transmission power control in a communication system. It isan object of the present invention to provide timely power control thatis necessary to provide robust communication link quality under fadingconditions.

In a mobile communications environment, the fading conditions of apropagation path change rapidly. This phenomenon is described in detailin the aforementioned U.S. Pat. No. 5,056,109. Communications stationsmust be able to respond to these sudden changes in the propagation path.The present invention provides a method and apparatus for responding tothe rapid changes in the communications channel of a mobilecommunication system.

In a code division multiple access (CDMA) communication system, themethods described herein have special significance, because by reducingthe transmission power to the minimum necessary for high qualitycommunications, the communication system provides less interference tothe transmissions of other users and allows an increase in overallsystem capacity. In addition, in a capacity limited system, the powerreduction of transmission to one user allows another user to transmit ata higher power level which may be necessary due to differences in thepropagation path or because that user is transmitting at a higher datarate.

Further, it should be noted that power control techniques are presentedin the exemplary embodiment in a spread spectrum communication system,however, the methods presented are equally applicable for othercommunication systems. Also, the exemplary embodiment used for thecontrol of transmission power in transmissions from a base station to aremote or mobile station may be applied to the control of transmissionpower in transmissions from a remote or mobile station to a basestation.

In the exemplary embodiment, a base station transmits packets of data toa mobile station. The mobile station receives, demodulates and decodesthe received packet. If the mobile station determines that the receivedpacket cannot be reliably decoded, it sets the normally ‘0’ qualityresponse power control bit to ‘1’ indicating the situation to the basestation. In response, the base station increases the transmission powerof the signal to the mobile station.

In the exemplary embodiment of the present invention, when the basestation increases its transmission power it does so with a relativelylarge step in transmission power which is assumed to be more thanadequate under most fading conditions. The base station then decreasesthe transmission power level at an exponentially decreasing rate as longas the quality response power control bits remain at ‘0’. In analternative embodiment, the base station responds to a request from themobile station for additional signal power by increasing the signalpower incrementally.

In an improved embodiment of this power control system, the base stationwill determine whether the error reported by the mobile station was of arandom nature in which case it will immediately begin ramping down thetransmission power or whether the error was an error resulting from agenuine fading condition. The base station distinguishes errors of arandom nature from those of a prolonged nature by examining the patternsof power control bits sent by the mobile station. If the pattern ofpower control request signals that the mobile station transmits back tothe base station indicates that there is a new fading condition presentin the propagation path, then the base station will refrain fromdecreasing the transmission power.

In an improved embodiment, the bases station examines the pattern ofincoming power control messages to determine characteristics of thefade. The estimation of the fading characteristics can be used toestimate the power control changes that need to be made. This could beachieved for example by making the power control in the base stationpredictive.

One of the identified sources of sudden changes in the propagation pathof a mobile station is a change in velocity relative to the position ofthe base station. That is, if the velocity towards the mobile station oraway from the mobile station is changing. In the present invention, themobile station determines that the velocity relative to the base stationis changing, and if necessary, sets the power control bits to requestadditional power from the base station to accommodate the change invelocity.

In a first exemplary embodiment, the mobile station is equipped with amotion sensor which may operate off of information from the speedometeror tachometer in the case of an automobile based mobile station. Themobile station then generates the power control signal in accordancewith the signal from the motion sensor.

In a second exemplary embodiment, the mobile station may sense a shiftin the received signal from the base station in order to sense motion.In the exemplary embodiment, the mobile station determines the changesin relative velocity by measuring the Doppler shift in the receivedpilot signal.

The present invention also provides a method and apparatus forcontrolling transmissions power levels of variable rate transmissions.This method broadcasts the variable rate frames of data at differentpower levels depending on the rate of the transmission. A plurality ofimplementations are disclosed for adjusting the transmission powerlevels in a variable rate communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, objects, and advantages of the present invention willbecome more apparent from the detailed description set forth below whentaken in conjunction with the drawings in which like referencecharacters identify correspondingly throughout and wherein:

FIG. 1 is an illustration of an exemplary mobile telephone system;

FIG. 2 is an illustration of the apparatus of the present invention;

FIG. 3 is an illustration of a curve illustrating the delay timeentailed in a closed loop power control system;

FIGS. 4 a–b is an illustration of plots of the frame error rate v.normalized bit energy for different rates; wherein FIG. 4 a the mobilestation is stationary and in FIG. 4 b the mobile station is in motion inFIG. 4B;

FIG. 5 illustrates an exemplary embodiment of the control processor fora single loop fixed difference implementation;

FIG. 6 illustrates an exemplary embodiment of the control processor fora single loop variable difference implementation;

FIG. 7 illustrates an exemplary embodiment of the control processor fora multiple loop, one loop per rate, implementation;

FIG. 8 illustrates an exemplary embodiment of the control processor fora multiple loop, one loop per frequent rate, implementation;

FIG. 9 illustrates an exemplary embodiment of the control processor fora multiple loop, one loop per rate, composite reference implementation;and

FIG. 10 illustrates an exemplary embodiment of the control processor fora single loop composite feedback implementation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the present invention is illustrated in anexemplary implementation in a mobile communication system forcontrolling the power of transmissions between base station 4 and mobilestation 6. Information may be provided to and from a public switchedtelephone network (PSTN) to system controller and switch 2, or may beprovided to and from controller and switch 2 by another base station ifthe call is a mobile station to mobile station communication. Systemcontroller and switch 2, in turn, provides data to and receives datafrom base station 4. Base station 4 transmits data to and receives datafrom mobile station 6.

In the exemplary embodiment the signals transmitted between base station4 and mobile station 6 are spread spectrum communication signals, thegeneration of the waveforms of which are described in detail in theabove mentioned U.S. Pat. No. 4,901,307 and U.S. Pat. No. 5,103,459. Thetransmission link for communication of messages from mobile station 6 tobase station 4 is referred to as the reverse link and the transmissionlink for communication of messages from base station 4 to mobile station6 is referred to as the forward link. In the exemplary embodiment, thepresent invention is used to control the transmission power of basestation 4. However, the methods of power control of the presentinvention are equally applicable to controlling the transmission powerof mobile station 6.

Referring to FIG. 2, base station 50 and mobile station 30 areillustrated in block diagram form showing the apparatus for providingcontrol of the transmission power of base station 50 of the presentinvention. If a communication link degrades, then the link quality canbe improved by increasing the transmission power of the transmittingdevice. In the exemplary embodiment of controlling transmission power ofbase station 50, some of the methods for determining that thetransmission power of base station 50 should be increased include:

-   (a) mobile station detection of frame errors on forward link;-   (b) mobile station detects that received power is low on forward    link;-   (c) mobile station to base station range is large;-   (d) mobile station location is poor;-   (e) mobile station change in velocity;-   (f) mobile station detects that received power on pilot channel is    low on forward link;-   (g) E_(c)/N₀ is low, where E_(c)/N₀ is the energy per chip on either    the traffic or pilot channel divided by the total received power;    and-   (h) decoder metrics, such as symbol metrics, are high.    Conversely, some of the methods for determining that the    transmission power of base station 50 should be decreased include:-   (a) mobile station quality responses to the base station show a low    frame error rate for the forward link;-   (b) mobile station detects that received power is high on forward    link;-   (c) base station to mobile station range is low;-   (d) mobile station location is good;-   (e) mobile station detects that received power on forward link pilot    channel is high; and-   (f) decoder metrics, such as symbol metrics, are low.

When base station 50 detects a need to modify the transmission power ofthe forward link, control processor 58 sends a signal specifying amodified transmission power to transmitter (TMTR) 64. The modified powersignal may simply indicate a need to increase or decrease thetransmission power or it may indicate an amount to change the signalpower or it may be an absolute signal power level. In response to themodified power level signal, transmitter 64 provides all transmissionsat the modified transmission power level.

It should be noted that data source 60 may source modem, facsimile orspeech data. Data source 60 may be a variable rate source that variesits transmission rate on a frame to frame basis throughout thetransmission or it may be able to vary rates only upon command. In theexemplary embodiment, data source 60 is a variable rate vocoder. Thedesign and implementation of a variable rate speech vocoder aredescribed in detail in the aforementioned U.S. Pat. No. 5,414,796. Theoutput from data source 60 is encoded by encoder 62 and input to trafficmodulator 63 for modulation and input to transmitter 64. Also input topilot modulator 65 is a synchronous pilot signal for transmission.

A need for modification of the transmission power may be indicated byany one of the conditions enumerated above or by any combination ofthose conditions. If the method of power control is based upon aposition related effect such as range or mobile station location, thenan external signal (LOCATION) is provided to control processor 58 ofbase station 50 indicative of the location condition. The rangecondition can be detected by base station 50. In an alternativeembodiment, the range condition can be detected by mobile station 30 andtransmitted to base station 50. In response to the detected rangecondition control processor 58 in base station 50 generates a controlsignal for modifying transmission power of transmitter 64.

In a closed loop power control implementation, power control signals areprovided from mobile station 30 to base station 50. Mobile station 30may determine the power control signal in accordance with received poweror alternatively in accordance with the detection of frame errors or anyother method previously discussed. The present invention is equallyapplicable to any link quality factors.

If the link quality factor used is received power, then the signal frombase station 50 received at mobile station 30 by antenna 38 is providedto receiver (RCVR) 42 which provides an indication of the received powerto control processor 46. If the link quality factor used is thedetection of frame errors, then receiver 42 downconverts and amplifiesthe signal providing the received signal to traffic demodulator 43. Ifthe traffic signal is accompanied by a pilot signal in order to providefor coherent demodulation then the received signal is also provided topilot demodulator 45 which demodulates the signal in accordance with apilot demodulation format and provides a timing signal to trafficdemodulator 43. Traffic demodulator 43 demodulates the received signalin accordance with a traffic demodulator format. In the exemplaryembodiment, traffic demodulator 43 and pilot demodulator 45 are CDMAspread spectrum demodulators, the design of which is described in theaforementioned U.S. Pat. Nos. 4,901,307 and 5,103,459. Trafficdemodulator 43 provides the demodulated signal to decoder 44. In a firstexemplary embodiment, decoder 44 performs error—detection decoding todetermine if errors have occurred. Error detection/correction decoders,such as the Viterbi trellis decoder, are well known in the art. In analternative embodiment, decoder 44 decodes the demodulated signal andthen re-encodes the decoded signal. Decoder 44 then compares there-encoded signal with the demodulated signal to obtain an estimate ofthe channel symbol error rate. Decoder 44 provides a signal indicatingan estimated channel symbol error rate to control processor 46.

Control processor 46 compares the received power or estimated channelsymbol error rate referred to generically as the link quality factoragainst a threshold or set of thresholds which may be static or varying.Control processor 46, then provides the power control information toeither encoder 34 or power control encoder (P.C. ENC.) 47. If the powercontrol information is to be encoded into the data frame, then the powercontrol data is provided to encoder 34. This method requires that anentire frame of data be processed before transmitting the power controldata, then encoded traffic data containing power control data areprovided to transmitter (TMTR) 36 through modulator 35. In analternative embodiment, the power control data may simply overwriteportions of the data frame or may be placed in predetermined vacantpositions in the transmission frame. If the power control dataoverwrites traffic data, then this may be corrected by forward errorcorrection techniques at base station 50.

In implementations that process a full frame of data before providingthe power control data, the delay waiting for a full frame to beprocessed is undesirable in fast fade conditions. The alternative is toprovide the power control data directly to modulator 35 where it may bepunctured into the outgoing data stream. If the power control data istransmitted without error correction coding then control processor 46outputs the power control data directly to modulator 35. If errorcorrection coding is desired for the power control data, controlprocessor 46 outputs the power control data to power control encoder 47which encodes power control data without regard to the outgoing trafficdata. Power control encoder 47 provides the encoded power control signalto modulator 35 which combines the encoded power control signal with theoutgoing traffic data provided from data source 32 through encoder 34 tomodulator 35. Transmitter 36 upconverts and amplifies the signal andprovides it to antenna 38 for transmission to base station 50.

The transmitted signal is received at antenna 52 of base station 50 andprovided to data receiver (RCVR) 54 where it is downconverted andamplified. Receiver 54 provides the received signal to demodulator 55which demodulates the received signal. In the exemplary embodiment,demodulator 55 is a CDMA spread spectrum demodulator which is describedin detail in the aforementioned U.S. Pat. Nos. 4,901,307 and 5,103,459.If the power control data is encoded within a frame of traffic data,then the traffic and power control data is provided to decoder 56.Decoder 56 decodes the signal and separates the power control signalfrom the traffic data.

If, on the other hand the power control data is not encoded with a fullframe of data but rather punctured into the transmission stream of data,then demodulator 55 demodulates the signal and extracts the powercontrol data from the incoming data stream. If the power control signalis not encoded then demodulator 55 provides the power control datadirectly to control processor 58. If the power control signal is encodedthen demodulator 55 provides the encoded power control data to powercontrol decoder (P.C. DEC.) 100. Power control decoder 100 decodes thepower control data and provides the decoded power control data tocontrol processor 58. The power control signal is provided to controlprocessor 58, which in accordance with the power control signal providesa control signal to transmitter 64 indicative of a modified transmissionpower level.

One of the inherent problems with closed-loop power control systems is arelatively slow response time, relative to an open-loop power controlsystem. For example, in a closed-loop power control system, when basestation 50 transmits a frame at an insufficient transmission energy tomobile station 30, mobile station 30 receives and decodes the frame,determines whether the frame is in error, prepares a power controlmessage indicating the frame error, then transmits the power controlmessage to base station 50, which decodes the frame, extracts the powercontrol message and adjusts the transmission power of transmitter 64. Inthe exemplary embodiment, this results in a four frame time lag beforecorrection is apparent at mobile station 30. Thus, if the propagationpath has deteriorated, four consecutive frames would be transmitted atthe insufficient frame energy before a frame is transmitted at theadjusted frame energy. In this delay period the fading condition mayhave substantially improved or deteriorated.

The following are methods by which to improve the responsiveness of aclosed loop power control system. In a first exemplary embodiment of thepresent invention, the base station assumes the worse case. Which isthat the propagation path has deteriorated during the four frame delayperiod. In response the base station increases the transmission energyto that user by a relatively significant amount ΔE so that theadjustment will be more than adequate to assure that the power adjustedframe will be properly received even if the propagation path hasdeteriorated in the interim. In the exemplary embodiment of a spreadspectrum communication system, this increase in power to mobile station30 causes less power to be available for other users who share theforward link. So the base station transmitter quickly reduces thetransmission energy for that user following the initial increase. In theexemplary embodiment, the base station increases the energy by a fixedamount ΔE and holds that value for a delay period to verify that theincrease in transmission energy has been effective and then decreasesthe transmission energy in accordance with a predetermined piecewiselinear function as illustrated in FIG. 3.

FIG. 3 illustrates a plot of the transmission energy (E) against time.At point A the base station 50 increases the transmission energy inresponse to a power adjustment request from mobile station 30. Basestation 50 increases the transmission energy by an amount ΔE to point B.Base station 50 holds transmission at that transmission energy for apredetermined delay period then reduces the transmission energy at aswiftly decreasing rate for a predetermined number of frames to point C.At point C, if the power control message from mobile station 30 stillindicates an excess of transmission energy, base station 50 continues todecrease the transmission energy, however, the rate of the decrease isless. Again, base station 50 decreases at this intermediate rate ofdecrease for a predetermined number of frames until point D. At point Dthe rate of decrease is again reduced to a final decreasing rate atwhich the transmission energy will continue to be decreased until basestation 50 reaches some minimum value or it is alerted again by anotherpower adjustment request from mobile station 30, which occurs at pointE. This power adjustment continues throughout the duration of theservice provided.

In an improved embodiment, the transmit power can also be decreased by alarger amount should the pattern of incoming power control messagesindicates that the transmission power is unnecessarily high. In theexemplary embodiment, control processor 58 includes a timer (not shown).The timer is reset each time a power control message is receivedindicating a received frame error. Should the timer elapse withoutreceipt of another power control message indicating a received frameerror, then control processor 58 directs transmitter 64 to drop thetransmission of outgoing frames by a larger amount than the incrementaldecrease.

Base station 50 performs the adjustment of the transmission energy withknowledge that after the transmission energy has been increased therewill be a delay before the received power control information willreflect the change in the forward link transmission power. If thepropagation channel suddenly worsens, base station 50 will receive aseries of consecutive power control requests, and there will be a delaybefore the power adjustment requests are responsive to the change inforward link transmission energy. During this delay period, base station50 should not continue to increase the transmission energy for eachreceived power adjustment request. This is the reason that the powerlevel is held constant for a predetermined delay period as illustratedin the period following point B of FIG. 3.

It should also be noted that errors in a mobile communication systemcome in two types. Those that are random and those that are the resultof a change in the propagation path. In the exemplary embodiment, whenbase station 50 receives a power adjustment request, it increases thetransmission power by ΔE as described previously. Then it ignores thepower adjustment requests and retains the same increased power level forthe delay period. In an alternative embodiment, base station 50 adjuststhe power in accordance with each power control message. However,smaller changes would typically be used. This minimizes the impact ofrandom errors.

One of the main influences that results in changes in thecharacteristics of the propagation path between mobile station 30 andbase station 50 is motion by mobile station 30 towards or away from basestation 50. Mobile station 30 may provide base station 50 withinformation indicating that the mobile station velocity is changing orit may actually provide its velocity relative to base station 50. If themobile station is simply providing an indication that its velocity ischanging, it may provide that information as a power adjustment requestsignal in anticipation of a change in the quality of the propagationpath.

In a first embodiment, mobile station 30 may sense the change invelocity by providing a sensor to operate in accordance with a signalfrom the automobile tachometer or speedometer (not shown). In analternative embodiment, mobile station 30 determines either a change inthe mobile/base station relative velocity or absolute velocity bychanges in the received signal from base station 50. Mobile station 30may detect a change in velocity or measure the absolute relativevelocity by measuring the Doppler effect on the incoming signal frombase station 50. In an alternative embodiment, base station 50 may alsodetect a change in the mobile/base station relative velocity or measurethe absolute relative velocity by measuring the Doppler effect on theincoming signal from mobile station 30.

The traffic signal provided by base station 50 may be accompanied by apilot signal in order to provide for coherent demodulation of thereceived traffic signal. Use of a pilot signal is described in U.S. Pat.Nos. 4,901,307 and 5,103,459, and mobile station 30 can alternativelysense changes in the relative velocity or the Doppler shift of the pilotsignal.

In a preferred embodiment, when base station 50 knows the velocity ofmobile station 30, the value of the incremental change in transmissionenergy, ΔE, will vary in accordance with this velocity. Thedetermination of the value of ΔE may be performed algorithmically or bya lookup table in control processor 46.

If base station 50 transmits a pilot signal along with the trafficsignal, the pilot signal can be thought of as a traffic signal thatcarries a predetermined bit stream known by mobile station 30. Mobilestation 30 demodulates the pilot channel in pilot demodulator 45 inorder to get timing information to enable mobile station 30 to performcoherent demodulation of the traffic channel. Because the pilot channeland the traffic channel are provided through similar if not identicalpropagation paths, there is a strong correlation between the strength ofthe received pilot signal and the strength of the received trafficsignal. By basing the generation of the power control signal on thepilot channel instead of the traffic channel, the delay betweenreceiving the signal transmitted from base station 50 and generating thepower control signal may be reduced.

Referring to FIG. 2, pilot modulator 65 provides a pilot signal totransmitter 64 and transmitter 64 of base station 50 provides the pilotsignal along with the traffic signal to antenna 52 for broadcast tomobile station 30. The transmitted signal is received at antenna 38 andprovided to receiver 42. Receiver 42 downconverts and amplifies thepilot signal and provides the received pilot signal to pilot demodulator45 which generates a quality estimate of the demodulated pilot signaland provides it to control processor 46. Control processor 46 generatesa power control signal in accordance with the quality estimate of thedemodulated pilot signal and the operation proceeds as describedpreviously.

In forward link transmissions being broadcast from base station 50 tomobile station 30, it is beneficial to minimize the transmitted powerwhile maintaining the modem performance. In the exemplary embodiment ofa code division multiple access (CDMA) communication system, thisminimization of transmission power leaves more power for other channelsusing the same power amplifier, while reducing interference to otherusers and systems on the same and near-by frequencies.

In the exemplary embodiment of a mobile communication system withvariable-rate transmissions, the performance difference between thepossible rates can be significant. For example, the transmission powerlevel of frames from base station 50, required to achieve a given frameerror rate (FER) can vary greatly among the rates. This is illustratedin FIG. 4 a. FIG. 4 a shows the variation of frame error rates v. thebit energy normalized by the noise energy (E_(b)/N₀).

In the exemplary embodiment, data is transmitted in frames. The presentinvention is equally applicable to continuous transmission systems. Thepresent invention is illustrated in an exemplary implementation of avariable rate communication system having four possible rates. In theexemplary embodiment, those rates are designated as full rate, halfrate, quarter rate and eighth rate. The present invention is equallyapplicable to any variable rate communication system which supports anynumber of possible rates.

FIG. 4 a illustrates that the required bit energy for a given frameerror rate depends strongly upon the rate of the frame, with full rateframes requiring the highest bit energy and eighth rate frames requiringthe lowest amount of bit energy. Thus, in the present invention thetransmission power required for the desired performance level is setseparately to take advantage of the differences in required minimumpower between the respective rates. In addition, the necessaryperformance for the different rates can also be different, since theeffect of a frame error on perceptual quality differs depending on therate of the frame. For example, a higher frame error rate may be moreacceptable for eighth rate frames than for full rate frames.

FIG. 4 b is provided to show that the required bit energy for a desiredperformance level can vary with time and conditions of usage. Forexample, when mobile station 30 is in motion relative to base station50, the required bit energies will vary more between the rates than whenmobile station 30 is standing still. FIG. 4 b is provided to illustratethe waterfall curves when mobile station 30 is in motion. Whereas FIG. 4a is provided to show the waterfall curves for the same mobile station30 communicating with the same base station 50 except that mobilestation 30 is not in motion. It is because of this variance that thepresent invention provides a means for varying the level of differencebetween the transmission power of the various rates.

The present invention discloses a variety of ways to apply fast powercontrol on the forward link, utilizing the difference in the requiredpower. It should be noted that each of the methods can be used inconjunction with any of the power control techniques described above.

Moreover, the present invention is also applicable for taking advantageof the different desired performance at different rates. For example, aframe error rate of 1% may be required of full rate frames because thoseare the most perceptually significant frames. However, a frame errorrate of 4% may be acceptable for eighth rate frames which primarilycarry background noise information. The methods disclosed in theprevious invention can easily account for these different frame errorrates simply by adjusting threshold values used to determine thenecessity of increasing or decreasing the transmission power.

The general power control method adjusts the transmission power levelbased on feedback from mobile station 30 of the occurrence of frameerrors. However, these methods are equally applicable to any of thepower control methods described above, such as those based on physicallocation or received power. In these exemplary embodiments, the mobilestation 30 is described as sending a frame quality indicator thatindicates whether the previous frame was received and properly decodedor whether a frame error occurred. The system is equally applicable incommunication systems where feedback is provided from mobile station 30in the eventuality of a frame error, simply by attributing the absenceof frame error indicator as equal to a frame quality indicatorindicative of a properly received frame.

In the exemplary embodiments, the frame quality indicator signal is fedback from mobile station 30. This frame quality indicator corresponds toa previously transmitted frame from base station 50. The rate of theframe transmitted by base station 50 is referred to herein as the framequality indicator rate. In the exemplary embodiments, base station 50knows the frame quality indicator rates, because it knows the rates offrames which it transmits and the round trip delay time from the sendingof a message from base station 50 to mobile station 30, and the time formobile station 30 to generate the frame quality indicator signal andtransmit that signal back to base station 50. The present invention isequally applicable to systems where mobile station 30 transmits anindication of the frame rate along with the frame quality indicatorsignal.

The first exemplary embodiment of methods utilizing the differences inrequired power between rates is referred to herein as the single loop,fixed difference method. In this exemplary embodiment, one rate servesas the reference rate. The transmission power level of the referencerate is actively tracked by control processor 58 to directly adjust thetransmission power of frames at that reference rate. The transmissionpower of the other rates are determined dependent upon the transmissionpower of the reference rate.

The power levels for each of the other rates are determined inaccordance with the level of the reference rate, so as to keep theperformance at the required levels. Since the performance for everyframe is estimated to be similar regardless of the rate, the feedbackabout the actual performance of each frame is given uniform significanceregardless of the rate of the frame to which it corresponds and can beused indiscriminately in making adjustments to the reference rate.

In the exemplary implementation, there are four possible rates asdescribed above (full, half, quarter and eighth rates). In the exemplaryembodiment, the reference rate is full rate and the power level of halfrate is set to be 1 dB below the power level of the full rate, quarterrate is 1.5 dB below the power level of the full rate and the eighthrate is 1.8 dB below the power level of the full rate. Control processor58 determines the power level for each of the rates based on thefeedback from mobile station 30 as described below and provides thisinformation to variable gain transmitter 64. Transmitter 64 sets thetransmit power for outgoing frames in accordance with this signal andthe rate of the frame. Transmitter 64 is provided with a signal fromvariable rate data source 60 indicative of the rate of the outgoingframes.

FIG. 5 illustrates an exemplary embodiment of control processor 58 forthe implementation of the single loop and fixed difference power controlmethod. The frame quality indicator (FQI) message received from mobilestation 30 is provided to gain adjust selector 102. Gain adjust selector102 can be implemented by programming of a microprocessor, microcontroller or logic array as is well known in the art.

In the exemplary embodiment, the FQI message has one of two possiblevalues. It is either a zero indicating correct reception of the frame bymobile station 30 or a one indicating the occurrence of a frame error.In the exemplary embodiment, gain adjust selector 102 outputs a selectedgain adjustment value in accordance with equation (1) below:$\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}} = {+ 1.0}}} \\{0,{{{then}\mspace{14mu}{GA}} = {- 0.01}}}\end{matrix} } & (1)\end{matrix}$where GA is the gain adjustment output by gain adjust selector 102.These numbers are selected on the basis of an acceptable frame errorrate of 1%. That is why the ratio of the decrease to the increase is onehundred. These values are purely exemplary in nature and will varydepending on the implementation and the desired performance of thesystem.

It should also be noted that the present invention is equally applicableto systems where the feedback specifies more information than can becontained in one bit of information. In those cases the gain adjustmentvalues can have more then two possible values, which will be selecteddepending upon the value of the FQI message. The FQI message can be anyone of the indicators enumerated previously in the application.

The gain adjustment (GA) value is provided to one input of summingelement 104. The value provided to the other input of summing element104 is the current transmit power level of the reference rate. In theexemplary embodiment, the reference rate is full rate. The output ofsumming element 104 is the adjusted reference rate transmit power level.This value is provided to variable gain transmitter 64, which willamplify full rate frames in accordance with this value.

The output of summing element 104 is, also, fed back to the input ofdelay element 106. Delay 106, in the exemplary embodiment, delays theinput to summing element 104 by the period of time between separatearrivals of frame quality indicator messages. In the exemplaryembodiment the delay is 20 ms. The implementation of such delays is wellknown in the art.

The transmit power levels of the other rates are determined based uponthe power level of the reference rate transmit power level. The fullrate transmit power is provided to dependent transmit power calculator107, which determines the half rate, quarter rate and eight ratetransmit power levels in accordance with the full rate transmit power inaccordance with a predetermined calculation format. In the exemplaryembodiment, dependent transmit power calculator 107 is implemented byprogramming a microprocessor, microcontroller or logic array which iswell known in the art.

In the exemplary embodiment of dependent transmit power calculator 107,the half rate, quarter rate and eight rate transmit power levels are afixed difference from the full rate transmit power. So in the exemplaryembodiment, the full rate transmit power level is provided to a summinginput of summing element 108. The value Δ_(half) is provided to asubtracting input of summing element 108. In the exemplary embodiment,Δ_(half) is equal to 1 dB. The value outputted by summing element 108 isthe half rate transmit power which in the exemplary embodiment is 1 dBless than the power level of full rate frames. This value is provided tovariable gain transmitter 64, which amplifies half rate frames inaccordance with this value.

It should be noted that in a practical implementation of the presentinvention the operation need not be performed by addition. For example,typically the half rate transmit power 3 dB less than the full ratetransmit power. Thus, the half rate transmit power is can be computed inabsolute terms by dividing the full rate transmit power by two asopposed to subtracting 3 dB from the full rate transmit power.

Similarly, the full rate transmit power level is provided to a summinginput of summing element 110. The value Δ_(quarter) is provided to asubtracting input of summing element 110. In the exemplary embodiment,Δ_(quarter) is equal to 1.5 dB. The value outputted by summing element110 is the half rate transmit power. This value is provided to variablegain transmitter 64, which amplifies quarter rate frames in accordancewith this value.

Lastly, the full rate transmit power level is provided to a summinginput of summing element 112. The value Δ_(eighth) is provided to thesubtracting input of summing element 112. In the exemplary embodiment,Δ_(quarter) is equal to 1.8 dB. The value output by summing element 112is the eighth rate transmit power which is 1.8 dB less than the powerlevel of full rate frames. This value is provided to variable gaintransmitter 64, which amplifies eighth rate frames in accordance withthis value.

It should be noted that all of the delta values (Δ_(half), Δ_(quarter)and Δ_(eighth)) provided above are purely for exemplary purposes andthat other values are equally applicable and are anticipated by thepresent invention.

The second exemplary embodiment of methods utilizing the differences inrequired power between rates is referred herein as single loop, variabledifference method. This exemplary embodiment attempts to keep theperformance at each of the rates within its respective range. However,the difference between the transmit power of the dependent rates and thereference rate adapts based on information compiled by the individualrates, for example the moving average of individual frame error rates.As the performance for a rate other than the reference rate deviatesfrom the desired level, its power level difference from the referencelevel is modified to negate the deviation. If the performance of thereference rate deteriorates the power level difference for all or someother rates are modified.

In the exemplary implementation, control processor 58 tracks theperformance (e.g., number of frame erasures in the last 100 frames) foreach of the rates. For example, if the eighth rate performance fallsbelow the desired performance level, the difference between the eighthrate power level and the reference rate power level is reduced,effectively increasing the eighth rate power level, if the eighth ratepower level is lower than the reference power level.

In the exemplary implementation, data source 60 provides a signalindicative of the rate of an outgoing frame to control processor 58, bywhich control processor 58 determines the rates of the frame qualityindicator messages. FIG. 5 shows a single stage filter comprised ofelements 104 and 106. The present invention could be more complexwherein the modified full rate transmit power could depend on aplurality of past generated full rate transmit power values. The designand implementation of such digital filters are well known in the art anddescribed in detail in the aforementioned U.S. Pat. No. 5,414,796.

Referring to FIG. 6, the received frame quality indicator bit isprovided to gain adjustment selector 200. Gain adjustment selector canbe implemented by programming a microprocessor, microcontroller or logicarray which is well known in the art. In the exemplary embodiment, gainadjustment selector 200 selects a gain adjustment value in accordancewith equation (1) above.

This gain adjustment value is provided to a summing input of summingelement 202. The input to the second input of summing element 202 is thecurrent value of the reference rate transmit power level. In theexemplary embodiment, the reference rate is full rate. The output ofsumming element 202 is the adjusted full rate transmit power. The fullrate transmit power is provided to variable gain amplifier 64 whichamplifies outgoing full rate frame in accordance with this value.

In addition, the adjusted full rate transmit power value is fed back todelay element 201. Delay 201, in the exemplary embodiment, delays theinput to summing element 202 by the period of time between separatearrivals of frame quality indicator messages. In the exemplaryembodiment this delay is 20 ms. The implementation of such delays iswell known in the art.

The received frame quality indicator message is also provided tode-multiplexer 204. De-multiplexer 204 outputs the frame qualityindicator message upon one of four outputs based upon the rate of theframe quality indicator. If the rate of the frame quality indicator isfull rate, then the frame quality indicator message is provided to fullrate frame error rate (FER) counter 206. Full rate FER counter 206tracks the number of full rate frame errors in a predetermined number offull rate frame transmissions. Counter 206 can be implemented using adigital counter or by a sliding window accumulator, the implementationsof which are well known in the art. In the exemplary embodiment, counter206 tracks the number of frame errors in the last 100 full rate frames.

If the rate of the frame quality indicator is half rate then the framequality indicator message is provided to half rate FER counter 208.Counter 208 tracks the frame errors in a predetermined number of priorhalf rate frames and can be implemented as described with reference tocounter 206 above. If the rate of the frame quality indicator is quarterrate, then the frame quality indicator message is provided to quarterrate FER counter 210. Counter 210 tracks the frame errors in apredetermined number of prior quarter rate frames and can be implementedas described above. If the rate of the frame quality indicator is eighthrate, then the frame quality indicator message is provided to eighthrate FER counter 212. Counter 212 tracks the frame errors in apredetermined number of prior eighth rate frames and can be implementedas described above.

The frame error rate statistics from each of counters 206, 208, 210 and212 are provided to delta calculator 214. Delta calculator 214determines the difference values, Δ_(half), Δ_(quarter) and Δ_(eighth),in accordance with a predetermined calculation format, based upon thevalues provided by the counters. For example, if the frame errorstatistics for the half rate are too high, then delta calculator 214will reduce the value of Δ_(half), effectively increasing the transmitpower level of eighth rate frames, if the half rate power level is lowerthan the reference level. Typically, the half rate transmit power willbe 3 dB less than the full rate transmit power.

In addition, it is not necessary that each of the difference valuesdepend on frame error counts from all of the counters. In the exemplaryembodiment, the value of Δ_(half) is based solely on the half rate FER,the output of counter 208; the value of Δ_(quarter) is based solely onthe quarter rate FER, the output of counter 210; but the value ofΔ_(eighth) is determined on both the full rate FER and the eighth rateFER, the outputs of counters 206 and 212.

In an improved embodiment, each of the difference values will alsodepend on the value of the full rate FER. In the improved embodiment, ifthe full rate FER is above a threshold value, it will indicate that thefull rate transmit power is being increased. Since the transmissionpower of the other rates is determined dependent upon the full ratetransmit power, the difference values are increased, when it appearsfrom the full rate FER value from full rate FER counter 206 that thefull rate transmit power is going to be increased. By increasing thedifference values the transmission power of the other rates iseffectively decreased, which allows the dependently set rates to “float”at their value when changes are made to the full rate transmit power.

Delta calculator 214 outputs three delta values, Δ_(half), Δ_(quarter)and Δ_(eighth). Delta calculator 214 can be implemented by programming amicroprocessor, micros controller or logic array as is well known in theart. The three delta values, Δ_(half), Δ_(quarter) and Δ_(eighth) areprovided to dependent rate calculator 215 along with the full ratetransmit power. Dependent rate calculator 215 determines the half rate,quarter rate and eighth rate transmit powers in accordance with itsinputs and a predetermined calculation format. Dependent rate calculator215 can be implemented by programming a microprocessor, microcontroller,or logic array which is well known in the art.

In the exemplary embodiment of dependent rate calculator 215, the threedelta values, Δ_(half), Δ_(quarter) and Δ_(eighth) are provided to thesubtracting inputs of summing elements 216, 218 and 220, respectively.The summing input of summing elements 216, 218 and 220 is provided withthe full rate transmit power level. The values of Δ_(half), Δ_(quarter)and Δ_(eighth) are subtracted from the full rate power level to yieldthe half rate, quarter rate and full rate power levels, respectively. Asdescribed above each of these values is provided to variable gaintransmitter 64, which amplifies outgoing half rate, quarter rate andeighth rate frames in accordance with these values.

The third exemplary embodiment of methods utilizing the differences inrequired power between rates is referred herein as multiple loop powercontrol method using one loop per rate. This method is similar to thesingle loop method described above, except that there is one loop foreach of the rates. These loops are independent of one another indetermining the transmission power levels of the rates which theycontrol.

For example, when a frame quality indicator message is received that iseighth rate frame, changes are made directly in response to this messageto the transmit power level of the eighth rate frames, but no changesare made to the power levels of the other three rates. Thus, each ofthese feedback loops takes into account only the feedback informationcorresponding to frames of its rate.

In the exemplary implementation, data source 60 provides a signalindicative of the rate of an outgoing frame to control processor 58, bywhich control processor 58 determines the rates of the frame qualityindicator messages.

Referring now to FIG. 7, the frame quality indicator message is providedto de-multiplexer 400. De-multiplexer 400 provides the frame qualityindicator message upon one of four outputs based upon the rate of theframe quality indicator message.

If the rate of the frame quality indicator message is full rate, thenthe frame quality indicator message is provided to the input of fullrate gain adjust selector 402. Selector 402, in response to the framequality indicator message, outputs a gain adjustment (GA_(full)) valuethat either increases or decreases the full rate transmit power. In theexemplary embodiment, the selector 402 selects the gain adjustment value(GA_(full)) in accordance with equation (2) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{full}} = {+ 1.0}}} \\{0,{{{then}\mspace{14mu}{GA}_{full}} = {- 0.01}}}\end{matrix} } & (2)\end{matrix}$where the FQI message has one of two possible values, either a zero “0”indicating correct reception of the frame by mobile station 30 or a one“1” indicating the occurrence of a frame error. In addition, the gainadjustment value is set to “0” if the frame quality indicator message iserased by the reverse link.

The gain adjustment value from selector 402, GA_(full), is provided to asumming input of summing element 406. The other summing input of summingelement 402 is supplied with the current value of the full rate transmitpower. Summing element 406 outputs the adjusted full rate transmit powerto variable gain transmitter 64. In addition the adjusted full ratetransmit power value is provided to delay 404, which delays provision ofthe adjusted full rate transmit power value to summing element 406 untilanother full rate frame quality indicator message is received.

If the rate of the frame quality indicator message is half rate, thenthe frame quality indicator message is provided to the input of halfrate gain adjust selector 408. Selector 408, in response to the framequality indicator message outputs a gain adjustment (GA_(half)) valuethat either increases or decreases the half rate transmit power. In theexemplary embodiment, the selector 408 selects the gain adjustment value(GA_(half)) in accordance with equation (3) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{half}} = {+ 0.500}}} \\{0,{{{then}\mspace{14mu}{GA}_{half}} = {- 0.005}}}\end{matrix} } & (3)\end{matrix}$where the FQI message has one of two possible values, either a zero “0”indicating correct reception of the frame by mobile station 30 or a one“1” indicating the occurrence of a frame error.

The gain adjustment value from selector 408, GA_(half), is provided to asumming input of summing element 410. The other summing input of summingelement 410 is supplied with the current value of the half rate transmitpower. Summing element 410 outputs the adjusted half rate transmit powerto variable gain transmitter 64. In addition the adjusted half ratetransmit power value is provided to delay 412, which delays provision ofthe adjusted half rate transmit power value to summing element 410 untilanother half rate frame quality indicator message is received.

If the rate of the frame quality indicator message is quarter rate, thenthe frame quality indicator message is provided to the input of quarterrate gain adjust selector 414. Selector 414, in response to the framequality indicator message, outputs a gain adjustment (GA_(quarter))value that either increases or decreases the quarter rate transmitpower. In the exemplary embodiment, the selector 414 selects the gainadjustment value (GA_(quarter)) in accordance with equation (4) below:$\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{quarter}} = {+ 0.300}}} \\{0,{{{then}\mspace{14mu}{GA}_{quarter}} = {- 0.003}}}\end{matrix} } & (4)\end{matrix}$where the FQI message has one of two possible values, either a zero “0”indicating correct reception of the frame by mobile station 30 or a one“1” indicating the occurrence of a frame error.

The gain adjustment value from selector 414, GA_(quarter), is providedto a summing input of summing element 416. The other summing input ofsumming element 416 is supplied with the current value of the quarterrate transmit power. Summing element 416 outputs the adjusted quarterrate transmit power to variable gain transmitter 64. In addition theadjusted quarter rate transmit power value is provided to delay 418,which delays provision of the adjusted quarter rate transmit power valueto summing element 416 until another quarter rate frame qualityindicator message is received.

If the rate of the frame quality indicator message is eighth rate, thenthe frame quality indicator message is provided to the input of eighthrate gain adjust selector 420. Selector 420, in response to the framequality indicator message, outputs a gain adjustment (GA_(eighth)) valuethat either increases or decreases the eighth rate transmit power. Inthe exemplary embodiment, selector 420 selects the gain adjustment value(GA_(eighth)) in accordance with equation (5) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{eighth}} = {+ 0.300}}} \\{0,{{{then}\mspace{14mu}{GA}_{eighth}} = {- 0.003}}}\end{matrix} } & (5)\end{matrix}$where the FQI message has one of two possible values, either a zero “0”indicating correct reception of the frame by mobile station 30 or a one“1” indicating the occurrence of a frame error.

The gain adjustment value from selector 420, GA_(eighth), is provided toa summing input of summing element 422. The other summing input ofsumming element 422 is supplied with the current value of the eighthrate transmit power. Summing element 422 outputs the adjusted eighthrate transmit power to variable gain transmitter 64. In addition theadjusted eighth rate transmit power value is provided to delay 424,which delays provision of the adjusted eighth rate transmit power valueto summing element 422 until another eighth rate frame quality indicatormessage is received.

As discussed previously, variable gain transmitter 64 amplifies theoutgoing frames in accordance with the transmit power levels determinedas described above.

The fourth exemplary embodiment of methods utilizing the differences inrequired power between rates is referred herein as multiple loop withone loop per frequent rate power control. This method is similar to thesingle loop method, except that there is one loop for each of the morefrequent rates. These loops are independent of one another indetermining the transmission power levels of the rates they control. Theframe quality indicator message about a frame of a certain rate beingtracked is used by the loop for that rate only. The power levels forrates without a loop are determined dependently from the power levels ofrates that are been tracked. The difference from those tracked rates canbe static or adaptive.

In the exemplary embodiment, the full rate and the eighth rate framesare the two most likely frame rates in the variable rate transmissions.These two rates are tracked by two independent loops to decide theirindividual power levels. The power levels of the half and quarter ratesare then derived from the current levels of the full and eighth rates.For example, the quarter rate power is half the distance between fulland eighth rate power levels and the half rate power level can be halfway between the quarter rate and full rate power levels.

In the exemplary implementation, data source 60 provides a signal tocontrol processor 58 indicating the rate of the outgoing frame. Controlprocessor 58 computes the new transmission power level and provides thisinformation to transmitter 64.

Referring to FIG. 8, the frame quality indicator message is provided tode-multiplexer 450, which outputs the frame quality indicator messageupon a selected output depending on the rate of the frame qualityindicator message.

If the rate of the frame quality indicator message is full rate, thenthe frame quality indicator signal is provided by de-multiplexer 450 tofull rate gain adjust selector 452. In the exemplary embodiment, fullrate gain adjust selector 452 can be implemented by programming amicroprocessor, microcontroller or logic array as is well known in theart. Full rate gain adjustment selector 452 selects a full rate gainadjustment (GA_(full)) value in accordance with equation (6) below:$\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{full}} = {+ 1.0}}} \\{0,{{{then}\mspace{14mu}{GA}_{full}} = {- 0.1}}}\end{matrix} } & (6)\end{matrix}$where the FQI message has one of two possible values, either a zero “0”indicating correct reception of the frame by mobile station 30 or a one“1” indicating the occurrence of a frame error.

The selected full rate gain adjustment (GA_(full)) value is provided toa first summing input of summing element 456. The second input tosumming element 456 is provided by delay element 458 and is the currentfull rate transmit power. Delay element 458 delays provision of thecurrent full rate transmit power until a full rate frame qualityindicator message is received. Summing element 456 adds the full rategain adjustment value to the current full rate transmit power todetermine an adjusted full rate transmit power. The adjusted full ratetransmit power is provided to variable gain transmitter 64 whichamplifies full rate frames in accordance with this signal.

When the frame quality indicator message is full rate, switch 469 isclosed and the computed full rate transmit power is provided to asumming input of summing element 457. The subtracting input of summingelement 457 is supplied with the value Δ_(eighth) a fixed value or bydelta calculator 464 to compute the new value of eighth rate transmitpower. In the exemplary embodiment, the value of Δ_(eighth) is static,but it is envisioned that the methods described above could be used tomake the value of Δ_(eighth) dynamic. This newly determined value isprovided to variable gain transmitter 64, which amplifies the outgoingeighth rate frame in accordance with this value.

If the frame quality indicator rate is eighth rate, the frame qualityindicator signal is provided to eighth rate gain adjust selector 454. Inthe exemplary embodiment, eighth rate gain adjust selector 454 can beimplemented by programming a microprocessor, microcontroller or logicarray as is well known in the art. In the exemplary embodiment, gainadjustment selector 454 selects a eighth rate gain adjustment(GA_(eighth)) value in accordance with equation (7) below:$\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{eighth}} = {+ 0.30}}} \\{0,{{{then}\mspace{14mu}{GA}_{eighth}} = {- 0.03}}}\end{matrix} } & (7)\end{matrix}$The selected eighth rate gain adjustment (GA_(eighth)) value is providedto a first summing input of summing element 466.

The second input to summing element 466 is provided by delay element 464and is the current eighth rate transmit power. Delay element 464provides the current value of the eighth rate transmit power only whenan eighth rate frame quality indicator message is received. Summingelement 466 adds the eighth rate gain adjustment value to the currenteighth rate transmit power to determine the new eighth rate transmitpower which is provided to variable gain transmitter 64, which amplifieseighth rate frames in accordance with this signal.

When the frame rate is eighth rate, switch 468 is closed and thecomputed eighth rate transmit power is provided to a first summing inputof summing element 459. The second summing input of summing element 459is supplied with the value Δ_(full), a fixed value or one computed bydelta calculator 481, to compute the new value of the full rate transmitpower. The full rate transmit power value is provided to variable gaintransmitter 64 which amplifies the outgoing full rate frames inaccordance with this value.

In a first exemplary embodiment, the values of the transmit power forhalf and quarter rate frames are determined by a fixed differencemethod. In this first implementation, the full rate transmit power isprovided to summing elements 470 and 472. The output of summing element470 is the half rate transmit power. In the fixed difference embodiment,Δ_(half) is a fixed value, which is subtracted from the full ratetransmit power to determine the half rate transmit power. This newlydetermined half rate transmit power is provided to variable gaintransmitter 64 which amplifies the outgoing half rate frames inaccordance with this value.

Similarly, in the fixed difference implementation, the full ratetransmit power is provided to summing elements 472. The output ofsumming element 472 is the quarter rate transmit power. In the fixeddifference embodiment, Δ_(quarter) is a fixed value, which is subtractedfrom the full rate transmit power to determine the quarter rate transmitpower. This newly determined quarter rate transmit power is provided tovariable gain transmitter 64 which amplifies the outgoing quarter rateframes in accordance with this value.

In an improved embodiment, the half rate transmit power is determined inaccordance with full rate transmit power and the eighth rate transmitpower. In the exemplary embodiment of this improved method, the halfrate transmit power is calculated as a power level half way between thefull rate transmit power and the eighth rate transmit power. In theimproved embodiment, the full rate transmit power and the eighth ratetransmit power are provided to power level calculator 480. Calculator480 computes the values of the half rate transmit power and the quarterrate transmit power in accordance with these values. The values Δ_(half)and Δ_(quarter) whether fixed or adaptive can be used by calculator 480to modify quarter rate transmit power and the half rate transmit powercalculated by calculator 480.

In an alternative embodiment, the values of Δ_(half) and Δ_(quarter) areadaptive values. In the variable difference exemplary embodiment,de-multiplexer 450 provides the frame quality indicator to one of fouroutputs based on the rate of the frame quality indicator message. If theframe quality indicator message is sent at full rate, the frametherefor, the frame quality indicator signal is provided to full rateframe error rate counter 456, which keeps track of the average number offrame errors for full rate frames as described above. If the framequality indicator rate message is sent at half rate, the frame qualityindicator signal is provided to half rate frame error rate counter 458,which keeps track of the average number of frame errors for half rateframes as described above. If the frame quality indicator rate messageis sent at quarter rate, the frame quality indicator signal is providedto quarter rate frame error rate counter 460, which keeps track of theaverage number of frame errors for quarter rate frames as describedabove. If the frame quality indicator rate message is sent at eighthrate, the frame quality indicator is provided to eighth rate frame errorrate counter 462, which keeps track of the average number of frameerrors for eighth rate frames as described above.

The frame error counts are provided from counters 456, 458, 460 and 462are provided to delta calculator 481. Delta calculator 481 determinesthe values of Δ_(half) and Δ_(quarter) in accordance with the valuesprovided from counters 456, 458, 460 and 462. Delta calculator 481 canbe implemented by programming a microprocessor, microcontroller or logicarray. Delta calculator 481 provides the values of Δ_(half) andΔ_(quarter) to summing elements 470 and 472, respectively. Summingelements 470 and 472 subtract the values of Δ_(half) and Δ_(quarter)from the value of the full rate transmit power to determine the halfrate transmit power and the quarter rate transmit power, respectively.These values are provided to variable gain transmitter 64 whichamplifies the outgoing half rate and quarter rate frame in accordancewith these signals as described above.

The fifth exemplary embodiment of methods utilizing the differences inrequired power between rates is referred herein as multiple loop, oneloop per rate, composite reference power control. This method can beimplemented using either fixed or adaptive weighting. This method issimilar to the single loop method, except that there is one loop foreach of the rates and the loop statistics are used together. These loopsare independent of one another. The feedback about a frame of a certainrate is tracked by that loop for that rate only, while the loops for allother loops are frozen at their current levels. However, the actualtransmission power level is jointly determined by the current values ofall the loop output.

Referring to FIG. 9, the frame quality indicator message is provided tode-multiplexer 500. De-multiplexer 500 provides the frame qualityindicator message on one of four outputs, in accordance with the rate ofthe frame quality indicator message.

If frame quality indicator rate message is full rate, de-multiplexer 500outputs the frame quality indicator message to full rate gain adjustselector 502. Gain adjust selector 502 outputs a gain adjustment(GA_(full)) value in accordance with equation (8) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{full}} = {+ 1.00}}} \\{0,{{{then}\mspace{14mu}{GA}_{ful}} = {- 0.01}}}\end{matrix} } & (8)\end{matrix}$The gain adjustment value is provided to summing element 510. Each ofselectors 502, 504, 506 and 508 can be implemented by programming amicroprocessor, microcontroller or logic array.

The second summing input of summing element 510 is the previouslycalculated output of summing element 510 which is provided by delayelement 514 through optional multiplexer 512. Delay element 514 providesthe previous output of summing element 510 whenever the rate of theframe quality indicator message is full rate.

Multiplexer 512 is optionally provided in order to refresh the input tosumming element 510 in case the loop value grows “stale”. In otherwords, the value of the output from summing element 510 becomesunacceptably different from the current required full rate transmitpower. In this embodiment, the value from summing element 510 is not thefull rate transmit power, but rather is a factor used in computing thefull rate transmit power.

The output of summing element 510 is provided to a first input ofmultiplier 518. The second input of multiplier 518 is a weighting valueW_(full) which weights the output of 510, in accordance with thesignificance of that value to the computation of the reference rate bycomposite reference calculator 520. In a first exemplary embodiment,W_(full) is a fixed value that is determined ahead of time. In analternative embodiment, W_(full) is a variable value determined byweighting factor calculator 516 in accordance with a set of parameters.Examples of parameters that might be used by weighting calculator 516include frame error statistics, frequency of frames at this rate, etc.The value output by multiplier 518 is provided to composite referencecalculator 520.

If the frame quality indicator rate is half rate, de-multiplexer 500outputs the frame quality indicator message to half rate gain adjustselector 504. In accordance with the frame quality indicator, gainadjust selector 504 outputs a gain adjustment value (GA_(half)) asdescribed in equation (9) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{half}} = {+ 0.500}}} \\{0,{{{then}\mspace{14mu}{GA}_{half}} = {- 0.005}}}\end{matrix} } & (9)\end{matrix}$The gain adjustment value, GA_(half), is provided to summing element522. The second summing input of summing element 522 is provided bydelay element 526 through optional multiplexer 524. Multiplexer 524 isoptionally provided in order to refresh the input to summing element 522in case the loop value grows “stale”. Delay element 526 delays provisionof the output of summing element 522 until the next half rate framequality indicator is received.

The output of summing element 522 is provided to a first input ofmultiplier 530. The second input of multiplier 530 is a weighting valueW_(half) which weights the output of 522 in accordance with thesignificance of that value to the computation of the reference rate bycomposite reference calculator 520. In a first exemplary embodiment,W_(half) is a fixed value. In an alternative embodiment, W_(half) is avariable value determined by weighting calculator 528, in accordancewith a set of parameters. Examples of parameters that might be used byweighting calculator 528 include frame error statistics, frequency offrames at this rate, etc. The value output by multiplier 530 is providedto composite reference calculator 520.

If the frame quality indicator rate is quarter rate, de-multiplexer 500outputs the frame quality indicator to quarter rate gain adjust selector506. In accordance with the frame quality indicator, gain adjustselector 506 outputs a gain adjustment value (GA_(quarter)) inaccordance with equation (10) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{quarter}} = {+ 0.500}}} \\{0,{{{then}\mspace{14mu}{GA}_{quarter}} = {- 0.005}}}\end{matrix} } & (10)\end{matrix}$The gain adjustment value, GA_(quarter), is provided to a first input ofsumming element 532. The second summing input of summing element 532 isprovided by delay element 536 through optional multiplexer 534.Multiplexer 534 is optionally provided in order to refresh the input tosumming element 532 in case the loop value grows “stale”. Delay element536 delays provision of the output of summing element 532 until the nextquarter rate frame quality indicator is received.

The output of summing element 532 is provided to a first input ofmultiplier 540. The second input of multiplier 532 is a weighting valueW_(quarter), which weights the output of summing element 532 inaccordance with the significance of that value to the computation of thereference rate by composite reference calculator 520. Compositereference calculator 520 can be implemented by programming amicroprocessor, microcontroller or logic array which is well known inthe art. In a first exemplary embodiment, W_(quarter) is a fixed value.In an alternative embodiment, W_(quarter) is a variable value determinedby weighting calculator 538 in accordance with a set of parameters.Examples of parameters that might be used by weighting calculator 538include frame error statistics, frequency of frames at this rate, etc.The value output by multiplier 540 is provided to composite referencecalculator 520.

If the frame quality indicator rate is eighth rate frame, de-multiplexer500 outputs the frame quality indicator to eighth rate gain adjustselector 508. In accordance with the frame quality indicator, gainadjust selector 508 provides a gain adjustment value (GA_(eighth)) inaccordance with equation (11) below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{eighth}} = {+ 0.500}}} \\{0,{{{then}\mspace{14mu}{GA}_{eighth}} = {- 0.005}}}\end{matrix} } & (11)\end{matrix}$The gain adjustment value is provided to a first input of summingelement 542. The input of the second summing input of summing element542 is provided by delay element 546 through optional multiplexer 544.Multiplexer 544 is optionally provided in order to refresh the input tosumming element 542 in case the loop value grows “stale”. Delay element546 delays provision of the output of summing element 542 until the nexteighth rate frame quality indicator is received.

The output of summing element 542 is provided to a first input ofmultiplier 550. The second input of multiplier 550 is a weighting valueW_(eighth), which weights the output of summing element 542 inaccordance with the significance of that value to the computation of thereference rate by composite reference rate calculator 520. In a firstexemplary embodiment, W_(eighth) is a fixed value. In an alternativeembodiment, W_(eighth) is a variable value determined by weightingcalculator 548 in accordance with a set of parameters. Examples ofparameters that might be used by weighting calculator 548 include frameerror statistics, frequency of frames at this rate, etc. The valueoutput by multiplier 550 is provided to composite reference calculator520.

Composite reference calculator 520 determines the value of the referencerate in accordance with the outputs of multipliers 518, 530, 540 and550. In the exemplary embodiment, the reference rate is full rate, soreference calculator 520 outputs the full rate transmit power tovariable gain transmitter 64 which amplifies the full rate frames forbroadcast in accordance with this value.

The full rate transmit power is provided to dependent transmit powercalculator 561. Dependent transmit power calculator 561 computes thehalf rate, quarter rate and eighth rate transmit power levels inaccordance with a predetermined calculation format and the full ratetransmit power. In an improved embodiment, dependent transmit powercalculator 561 operates with difference values that can be fixed orvariable.

In the exemplary embodiment of dependent transmit power calculator 561,the half rate, quarter rate and eight rate transmit powers aredetermined simply by subtracting the values of Δ_(half), Δ_(quarter) andΔ_(eighth) from the full rate transmit power. In the exemplaryembodiment of dependent transmit power calculator 561, the full ratetransmit power is provided to the summing input of summing elements 562,564 and 566.

The subtracting input of summing element 562 is provided with the valueΔ_(half). The output of summing element 562 is the half rate transmitpower which is provided to variable gain transmitter 64, which amplifiesthe half rate frames for broadcast in accordance with this value. Thesubtracting input of summing element 564 is provided with the valueΔ_(quarter). The output of summing element 564 is the quarter ratetransmit power, which is provided to variable gain transmitter 64, whichamplifies the quarter rate frames for broadcast in accordance with thisvalue. The subtracting input of summing element 566 is provided with thevalue Δ_(eighth). The output of summing element 566 is the eighth ratetransmit power which is provided to variable gain transmitter 64, whichamplifies the eighth rate frames for broadcast in accordance with thisvalue.

In a first exemplary embodiment, Δ_(half), Δ_(quarter) and Δ_(eighth)are fixed values. In an alternative embodiment, the values of Δ_(half),Δ_(quarter) and Δ_(eighth) are variable. In the variable differenceexemplary embodiment, de-multiplexer 500 provides the frame qualityindicator to one of four outputs based on the value of the frame ratesignal.

If the frame quality indicator message is full rate, the frame qualityindicator message is provided to full rate frame error rate counter 552,which keeps track of the frame error rate of full rate frames. If theframe quality indicator message is half rate, the frame qualityindicator message is provided to half rate frame error rate counter 556,which keeps track of the frame error rate for half rate frames. If theframe quality indicator message is quarter rate, the frame qualityindicator message is provided to quarter rate frame error rate counter558, which keeps track of the frame error rate for quarter rate frames.If the frame quality indicator message is eighth rate, the frame qualityindicator signal is provided to eighth rate frame error rate counter560, which keeps track of the frame error rate for eighth rate frames.

The frame error counts from counters 552, 556, 558 and 560 are providedto delta calculator 554. Delta calculator 554 can be implemented byprogramming a microprocessor, microcontroller or logic array as is wellknown in the art. Delta calculator 554 determines the values ofΔ_(half), Δ_(quarter) and Δ_(eighth) in accordance with the valuesprovided from counters 552, 556, 558 and 560. Delta calculator 554provides the values of Δ_(half), Δ_(quarter) and Δ_(eighth) to summingelements 562, 564 and 566, respectively. Summing elements 562, 564 and566 subtract the adjusted values of Δ_(half), Δ_(quarter) and Δ_(eighth)from the value of the full rate transmit power to determine the halfrate transmit power, quarter rate transmit power and eighth ratetransmit power, respectively. These values are provided to variable gaintransmitter 64 which amplifies the outgoing half rate, quarter rate andeighth rates frame in accordance with these signals.

The sixth exemplary embodiment of methods utilizing the differences inrequired power between rates is referred herein as single loop,composite feedback. In this embodiment, the gain adjustment selectorscan either be static or dynamic. As each frame quality indicator messageis received that message is used to directly adjust the transmit powerof the reference rate.

In the exemplary implementation, data source 60 provides a signal tocontrol processor 58 indicating the rate of the outgoing frame of data.Control processor 58 provides a signal indicative of the calculatedtransmission power levels for different rates to transmitter 64.Variable gain transmitter 64 amplifies the outgoing frame in accordancewith the calculated power levels.

Referring to FIG. 10, the frame quality indicator message is provided tode-multiplexer 600. In accordance with rate of the frame qualityindicator message, de-multiplexer 600 outputs the frame qualityindicator message on one of four outputs. If the rate of the framequality indicator message is full rate, then the frame quality messageis output to full rate gain adjustment selector 602. In the exemplaryembodiment, full rate gain adjustment selector 602 determines selectsgain adjustment (GA_(full)) signal in accordance with equation (12)below: $\begin{matrix}{{{if}\mspace{14mu}{FQI}} = \{ \begin{matrix}{1,{{{then}\mspace{14mu}{GA}_{full}} = {+ 1.00}}} \\{0,{{{then}\mspace{14mu}{GA}_{full}} = {- 0.01}}}\end{matrix} } & (12)\end{matrix}$where FQI is the frame indicator message with 1 indicating theoccurrence of a frame error and 0 indicating the absence of a frameerror.The gain adjustment value, GA_(full), is provided through multiplexer610 to a first input of summing element 612. The second input of summingelement 612 is provided with the current value of the reference ratetransmit power, which in the exemplary embodiment the full rate transmitpower.

If the rate of the frame quality indicator message is half rate, thenthe frame quality message is output to half rate gain adjustmentselector 604. In the exemplary embodiment, half rate gain adjustmentselector 604 selects gain adjustment value (GA_(half)) in accordancewith equation (13) below: $\begin{matrix}{{GA}_{half} = \{ \begin{matrix}0.500 & {{{if}\mspace{14mu}{FQI}} = 1} \\{- 0.005} & {{{if}\mspace{14mu}{FQI}} = 0}\end{matrix} } & (13)\end{matrix}$where FQI is the frame indicator message with 1 indicating theoccurrence of a frame error and 0 indicating the absence of a frameerror.The gain adjustment value, GA_(half), is provided through multiplexer610 to a first input of summing element 612. The second input of summingelement 612 is provided with the current value of the reference ratetransmit power.

If the rate of the frame quality indicator message is quarter rate, thenthe frame quality message is output to quarter rate gain adjustmentselector 606. In the exemplary embodiment, quarter rate gain adjustmentselector 606 selects a gain adjustment value, GA_(quarter), inaccordance with equation (14) below: $\begin{matrix}{{GA}_{quarter} = \{ \begin{matrix}0.300 & {{{if}\mspace{14mu}{FQI}} = 1} \\{- 0.003} & {{{if}\mspace{14mu}{FQI}} = 0}\end{matrix} } & (14)\end{matrix}$where FQI is the frame indicator message with 1 indicating theoccurrence of a frame error and 0 indicating the absence of a frameerror.The gain adjustment value, GA_(quarter), is provided through multiplexer610 to a first input of summing element 612. The second input of summingelement 612 is provided with the current value of the reference ratetransmit power.

If the rate of the frame quality indicator message is eighth rate, thenthe frame quality message is output to eighth rate gain adjustmentselector 608. In the exemplary embodiment, eighth rate gain adjustmentselector 608 selects a gain adjustment value, GA_(eighth), in accordancewith equation (15) below: $\begin{matrix}{{GA}_{eighth} = \{ \begin{matrix}0.100 & {{{if}\mspace{14mu}{FQI}} = 1} \\{- 0.001} & {{{if}\mspace{14mu}{FQI}} = 0}\end{matrix} } & (15)\end{matrix}$where FQI is the frame indicator message with 1 indicating theoccurrence of a frame error and 0 indicating the absence of a frameerror.The gain adjustment value, GA_(eighth), is provided through multiplexer610 to a first input of summing element 612. The second input of summingelement 612 is provided with the current value of the reference ratetransmit power. Selectors 602, 604, 606 and 608 can be implemented byprogramming a microprocessor, microcontroller or logic array as is wellknown in the art.

After determining the reference rate transmit power, the transmissionpower for the remaining rate is determined in accordance with thatvalue. The full rate transmit power is provided to dependent transmitpower calculator 625 which computes the half rate, quarter rate andeighth rate transmit powers in accordance with the full rate transmitpowers. In a first exemplary implementation of dependent transmit powercalculator 625, Δ_(half), Δ_(quarter) and Δ_(eighth) are fixed values.Thus, full rate transmit power is provided to summers 626, 628 and 630.And the values Δ_(half), Δ_(quarter) and Δ_(eighth) are subtracted fromthe full rate transmit power to determine the half rate transmit power,the quarter rate transmit power and the eighth rate transmit power,respectively.

In an alternative embodiment, the values of Δ_(half), Δ_(quarter) andΔ_(eighth) are variable. In the variable difference exemplaryembodiment, de-multiplexer 500 provides the frame quality indicator toone of four outputs based on the value of the frame rate signal.

If the rate of the frame quality indicator message is full rate, theframe quality indicator signal is provided to full rate frame error ratecounter 616, which keeps track of the frame error rate for full rateframes. If the rate of the frame quality indicator message is half rate,the frame quality indicator message is provided to half rate frame errorrate counter 618, which tracks the frame error rate of half rate frames.If the rate of the frame quality indicator message is quarter rate, theframe quality indicator signal is provided to quarter rate frame errorrate counter 620, which tracks the frame error rate for quarter rateframes. And if the rate of the frame quality indicator message is eighthrate, the frame quality indicator signal is provided to eighth rateframe error rate counter 622, which tracks the frame error rate foreighth rate frames.

The frame error counts from counters 616, 618, 620 and 622 are providedto delta calculator 624. Delta calculator 624 determines the values ofΔ_(half), Δ_(quarter) and Δ_(eighth) in accordance with the valuesprovided from the counters. Delta calculator 624 can be implemented byprogramming a microprocessor, microcontroller or logic array as is wellknown in the art. Delta calculator 624 provides the values of Δ_(half),Δ_(quarter) and Δ_(eighth) to summing elements 626, 628 and 630,respectively. Summing elements 626, 628 and 630 subtract the calculatedvalues of Δ_(half), Δ_(quarter) and Δ_(eighth) from the value of thefull rate transmit power to determine the half rate transmit power,quarter rate transmit power and eighth rate transmit power,respectively. These values are provided to variable gain transmitter 64which amplifies the outgoing half rate, quarter rate and eighth ratesframe in accordance with these signals.

The previous description of the preferred embodiments are provided toenable any person skilled in the art to make or use the presentinvention. The various modifications to these embodiments will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other embodiments without the use ofthe inventive faculty. Thus, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosedherein.

1. A method for controlling transmission power of variable rate framesof data, comprising: receiving a frame quality message from a remotecommunication station; receiving a gain adjustment value and a previousreference rate transmit value, and summing said gain adjustment valueand said previous reference rate transmit value to provide a referencerate transmit power level; determining at least one additional transmitpower level in accordance with said reference rate transmit power leveland providing a transmit power signal based at least in part on said oneadditional transmit power level; and amplifying said variable rateframes in accordance with said transmit power signal and a rate of saidvariable rate frames of data.
 2. The method of claim 1 furthercomprising: receiving said reference rate transmit power level and afixed difference value; and summing said reference rate transmit powerlevel and said fixed difference value to determine said at least oneadditional transmit power level.
 3. The method of claim 1 furthercomprising: receiving said reference rate transmit power level and avariable difference value; and summing said reference rate transmitpower level and said variable difference value to determine said atleast one additional transmit power level.
 4. The method of claim 3further composing: determining at least one frame error rate value; andusing said at least one frame error rate value to determine saidvariable difference value.
 5. The method of claim 4 further comprising:receiving said frame quality message and outputting said frame qualitymessage upon a selected output in accordance with a frame qualitymessage rate; and counting said frame quality message rate upon theselected output.
 6. An apparatus for controlling transmission power ofvariable rate frames of data comprising: means for receiving a framequality message from a remote communication station; means for receivinga gain adjustment value and a previous reference rate transmit value,and summing said gain adjustment value and said previous reference ratetransmit value to provide a reference rate transmit power level; meansfor determining at least one additional transmit power level inaccordance with said reference rate transmit power level and providing atransmit power signal based at least in part on said one additionaltransmit power level; and means for amplifying said variable rate framesin accordance with said transmit power signal and a rate of saidvariable rate frames of data.
 7. The apparatus of claim 6 furthercomprising; means for receiving said reference rate transmit power leveland a fixed difference value; and means for summing said reference ratetransmit power level and said fixed difference value to determine saidat least one additional transmit power level.
 8. The apparatus of claim6 further comprising: means for receiving said reference rate transmitpower level and a variable difference value; and means for summing saidreference rate transmit power level and said variable difference valueto determine said at least one additional transmit power level.
 9. Theapparatus of claim 8 further comprising: means for determine at leastone frame error rate value; and means for using said at least one frameerror rate value to determine said variable difference value.
 10. Theapparatus of claim 9 further comprising: means for receiving said framequality message and outputting said frame quality message upon aselected output in accordance with a frame quality message rate; andmeans for counting said frame quality message rate upon the selectedoutput.